Crystal paper having metallic luster

ABSTRACT

A crystal paper having a metallic luster which is prepared by uniformly dispersing (A) either (1) crystals of an inorganic metal salt or (2) a crystalline organic compound and (B) metal powder together with (C) a film-formable substance, onto a supporting paper having a smooth surface. Two layers may be applied to the paper with metal flakes being present in one of the layers.

ited States Patent Imai 1 Mar. 7, 1972 [54] CRYSTAL PAPER HAVING METALLIC References Cit d LUSTER UNITED STATES PATENTS [7 Inventor: Hisao lmai, ji, Japan 2,146,619 2/1939 Bowlby ....117/157 [73] Assignee: Goji Paper Mfg. Co., Ltd., Flu-hi, 1,011,181 12/1911 Galay..... ....1l7/15 7 Shiguoka-ken Japan 2,362,884 11/1944 Clark .1. ...1l7/l52 X 2,872,340 2/1959 Newman et al.. ...l17/157 X [22] Filed: Dec. 3, 1969 2,671,734 3/1954 Rosenblum ...1 17/157 X pp 881863 1,801,313 4/1931 Kiefer ..1l7/157 Primary Examiner-Murray Katz [30] Foreign Application Priority D m Assistant Examiner-M. R. Lusignan Attorney-Woodhams, Blanchard and Flynn Sept. 12, 1969 Japan ..44/72519 [57] ABSTRACT [52] U.S.Cl. ..117/71 R, 117/42, 1 17/154,

117/155 L, 117/156, 117/ 167, 1 17/159, 117/160 R A crystal paper havmg a metalhc luster whlch 1s prepared by 51 1111.01 ..B32b 29/04 "nifmmly dispersing (A) either (1) crystals [58 Field ofSearch ..117/159- 117/36.2 152 157, metal salt (2) a "Ymmne ganic and (3) 7/160 R 71 R 73 76 P 6 154 159 metal powder together with (C) a film-formable substance, onto a supporting paper having a smooth surface. Two layers may be applied to the paper with metal flakes being present in one of the layers.

10 Claims, No Drawings CRYSTAL PAPER HAVING METALLIC LUSTER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal paper having a metallic luster which is prepared by uniformly dispersing crystals of an inorganic metal salt or a crystalline organic compound and metal powder, together with a film-formable substance, onto a supporting paper.

2. Description of the Prior Art A crystal paper having a metallic luster and a method of preparing same have been unknown to date. But, a method of preparing a crystal paper having no metallic luster has already been a matter of common knowledge. According to this wellknown method, an inorganic metal salt and a water-soluble film-formable substance such as dextrin are dissolved in water and the resultant aqueous solution is applied onto a supporting paper. Because the thus obtained crystal paper is lacking in water-resisting properties, it is usually subjected to a process of applying a waterproof coating onto its crystallized surface thereafter. The inventor of the present invention has proposed in Ser. No. 881,860, filed Dec. 3, 1969, a method of preparing a crystal paper by coating an organic solvent solution comprising a crystalline organic compound such as acetanilide and a tilm-formable substance such as nitrocellulose, soluble in the organic solvent, onto a supporting paper.

The present invention has been accomplished on the basis of the foregoing method proposed by the inventor as well as the prior art.

SUMMARY OF THE INVENTION The object of the present invention is to provide a crystal paper having a metallic luster which is prepared by dispersing, onto a supporting paper, crystals of an inorganic metal salt or a crystalline organic compound and metal powder as the principal components thereof.

For the purpose of preparing a crystal paper having a metallic luster, a method such as employing a supporting paper prepared by laminating a metal leaf on a sheet of paper and coating it with an organic solvent solution as described above may be thought of. However, said method, when actually employed, fails to produce the intended crystal paper having a beautiful metallic luster. This is attributable to the fact that the separated crystals cover the surface of the metal leaf, thereby hampering the full display of the luster peculiar to said metal.

As for the film-formable substance in the present invention, natural or synthetic high-molecular compounds capable of forming a film upon the evaporation of solvent, such as nitrocellulose, dextrin, polyvinyl acetate, modified phenol resin, etc., are applicable. As for the inorganic metal salt suitable for the present invention, such ones as are used for common crystal papers not having a metallic luster, for instance, magnesium sulfate, barium chloride, ammonium sulfate, stannous chloride, etc., are applicable.

As for the crystalline organic compound, one having a comparatively high-melting point is desirable; whereas one having a comparatively low-melting point, say, below 50 C., is undesirable in view of the fact that, although it is capable of temporarily forming a crystal surface at a high temperature in the summer season, said crystal surface is easily lost or gets blurred thereafter. Further, a compound vulnerable to deliquescence and/or sublimation at room temperature is also undesirable. Accordingly, for the crystalline organic compound suitable for the present invention, there may be enumerated such dye intermediates as o-aminophenol, 2,4- dinitrophenol, p-nitroaniline, resorcinol, 3-hydroxy-2- naphthoic acid and anthraquinone-sulfonic acid. In addition, acetanilide, acetoacetic anilide, dirnethyl terephthalate, pchloroaniline, etc., are also applicable.

The employment of said inorganic metal salt or crystalline organic compound is for the purpose of providing an uniform crystal pattern for the supporting paper. For the solvent, there is employed water or an organic solvent. As for said organic solvent, one member or two or more members of the group of ordinary solvents such as methanol, ethanol, benzene, methyl ethyl ketone, acetone, Cellosolve and methyl Cellosolve are selected. Cellosolve is a trade name for ethylene glycol monoethyl ether. In this connection, it is to be noted that, a single organic solvent is rarely employed, but it is usual to employ two or more solvents in combination.

When a plural number of organic solvents are to be employed, it is required that they be mutually soluble. The reason for thus employing combined solvents is for the purpose of controlling the evaporation period thereof and enhancing the solubility of the film-fonnable substance employed.

The employment of said metal powder is for the purpose of providing a metallic luster for the crystal paper, and such metal powders as are used for the so-called gold-printing or silver-printing in the conventional art of printing are applicable. That is,.when a golden color, is to be provided, brass powder (comprising -90 percent of copper and 20-10 percent of zinc) is employed, while when a silver color is to be provided, aluminum powder is employed. In either case, a metal powder having the form of flakes and a grain size of about 0.3;.tXl0pX30u is suitable. When its grain size is smaller than the above, an inferior metallic luster will result, whereas when said size is larger than the above, although the resultant metallic luster may be satisfactory, it will be difficult to employ said metal powder for coating by means of a gravure cylinder. As for the supporting paper, an ordinary paper sheet having a smooth surface or a processed paper such as cast-coated paper, that is, a paper sheet subjected to a calendering finish or a supercalendering finish or a treated paper with a coated surface having a luster provided by coating with a heated glossy metal surface, is applicable.

The preparation of a crystal paper according to the present invention is easily performed by the following processes. When water is employed as the solvent, it suffices to coat the supporting paper with a dispersed solution prepared by mixing an inorganic metal salt to the extent of 15-50 percent by weight of the resulting solution, a water-soluble, film-formable substance such as dextrin to the extent of 10-25 percent by weight of said solution and, in addition, the foregoing metal powder to the extent of 5-30 percent by weight of the solution and to dry it thereafter, thereby separating crystals of said metal salt, like in the prior art. On this occasion, the amount of said metal powder contained in the crystal layer is in the range of 1-10 gr./m But, as the crystal surface thus obtained does not possess water-resisting properties yet, it is usual to apply an additional water-resisting coat thereon. Application of said water-resisting coat is performed by coating with a water-resisting, film-formable substance such as a xylene solution of modified phenol resin. The film of said water-resisting coat is desired to have a thickness of 4-12 grim. However, when a water-resisting crystal paper is to be prepared, it is preferred to take such steps that an aqueous solution comprising an inorganic metal salt and a water-soluble, film-formable substance is first coated onto a supporting paper (to the extent of about 15 grJm) in order to separate the crystals of the metal salt, and thereafter a solution prepared by dispersing metal powder in an organic solvent solution comprising a varnish, i.e., a water-resisting, film-forrnable substance as described above is coated onto the crystal surface. On this occasion, a mixed solution prepared by mixingmetal powder in the amount of about 50 weight percent in a varnish consisting of an organic solvent in the amount of 50-60 weight percent and a film-formable substance in the amount of 50-40 weight percent is employed. For the purpose of coating said solution, it is convenient to employ a gravure cylinder. The appropriate amount of coating is about 8 grJm, and the amount of metal powder to be contained in the water-resisting coat is in the range of 36 grJm.

When an organic solvent containingthe crystalline organic compound is applied, on the other hand, a dispersed solution prepared by employing such a solvent as xylene, toluene or acetone and adding thereto a film-formable (and water-resisting) substance such as modified phenol resin in the amount of about 50 weight percent and further mixing therein metal powder in the amount of about 30-40 weight percent is employed. As for the coating work thereof, it is convenient to employ a roll-coater or a bar-coater, and the appropriate amount of coating is in the range of -30 gr./m. and preferably about 20 gr./m. When an organic solvent is employed, just one coat willsuffice for obtaining a water-resisting crystal paper. The crystal layer thus formed contains the crystalline organic compound in the amount of 4-15 gr./m. the metal powder in the amount of 2-10 gin/m and the water-resisting, film-forrnable substance in the amount of 5-l 8 gr./m.

In either case, the appropriate temperature for drying is in the range of l5-45 C. Further, according to the present invention, a viscosity-improving agent such as sodium alginate and a coloring agent such as dye may be also added to the solution for coating or the dispersed solution.

The product thus prepared is a crystal paper having a beautiful metallic luster and, therefore, it serves not only as a very tasteful material for packing but also for various purposes such as gorgeous wallpapers and so forth.

As seen in the foregoing, according to the present invention, preparation of a crystal paper having a beautiful metallic luster is possible by coating a solution comprising an inorganic metal salt or a crystalline organic compound and film-formable substance onto a supporting paper and merely mixing, in said solution, metal powder for use in common printing, during the manufacturing process of said crystal paper. Therefore, the present invention has the advantage of not requiring the expensive laminated paper with a metal leaf for a supporting paper and, besides, it can provide a product having an appearance superior in metallic luster to that employing a metallaminatd paper as above. Moreover, in case of a solution employing an organic solvent for its solvent, just one coating thereof can provide a water-resisting crystal paper having a metallic luster, and if such a lustrous supporting paper as a cast-coated paper is employed, there will be obtained a crystal paper of further brilliant metallic luster.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 In a mixture consisting of 100 parts by weight of ethanol and 20 parts by weight of methyl ethyl ketone were dissolved 30 parts by weight of rosin modified phenol resin, 10 parts by weight of acetanilide, 10 parts by weight of nitrocellulose and 40 parts by weight of aluminum powder in order. The resultant solution was coated to the extent of 20 gr./m. onto a supporting paper and then dried at 20-35 C., thereby producing a crystal paper having a silvery luster.

EXAMPLE 2 A solution prepared by dissolving 80 parts by weight of magnesium sulfate (MgSOflHJl), 5 parts by weight of dextrin and 5 parts by weight of sodium alginate in order in 100 parts by weight of water was coated to the extent of gr./m. onto a supporting paper and then dried at a temperature of 25-27 C. Subsequently, thus obtained crystal surface was coated with a mixture comprising a varnish consisting of 50 parts by weight of a rosin modified phenol resin and 50 parts by weight of xylene and 5 weight percent of aluminum powder mixed therein to the extent of 7 gr./m. and then dried at the same temperature as above, whereby a crystal paper having a silvery luster was obtained.

EXAMPLE 3 A solution prepared by dissolving 80 parts by weight of magnesium sulfate (MgSO -7H 0), 15 parts by weight of gum arabic, 0.5 parts by weight of Chrysophenine as yellow dye, 25

arts by weight of aluminum Bowder and 5 parts by weight of rass powder in order in 10 parts by weight 0 water was coated to the extent of 20 grJm. onto a supporting paper and then dried at 25-27 C. Subsequently, thus obtained crystal surface having metallic luster was coated a varnish consisting of 100 parts by weight of acetone, 20 parts by weight of methyl ethyl ketone and 15 parts by weight of nitrocellulose to the extent of 7 gr./m. in order, and thus the crystal surface was provided with water-resisting property.

What we claim is:

l. A crystal paper having a metallic luster, comprising a paper substrate, a first coating layer on said paper substrate and consisting essentially of 1) crystals of an inorganic metal salt selected from the group consisting of magnesium sulfate, barium chloride, ammonium sulfate and stannous chloride and (2) metal flakes, dispersed in a water-soluble film-forming substance, said first coating layer containing l-l0 g./m. of metal flakes, and a second coating layer on top of said first coating layer, said second coating layer consisting essentially of a substantially water-insoluble film-fonning substance.

2. A crystal paper as defined in claim 1, wherein said first coating layer consists of magnesium sulfate, gum arabic, aluminum flakes and brass flakes, while said second coating layer consists of nitrocellulose.

3. A crystal paper as defined in claim 1, wherein said metal powder has the form of flakes of a size of about 0.3[LX10 30p.4.

A crystal paper having a metallic luster, comprising a paper substrate, a first coating layer on said paper substrate and consisting essentially of crystals of an inorganic metal salt selected from the group consisting of magnesium sulfate, barium chloride, ammonium sulfate and stannous chloride and a water-soluble film-forming substance, and a second coating layer on top of said first coating layer and consisting. essentially of metal flakes dispersed in a substantially water-insoluble film-forming substance, said second coating layer containing 3-6 g./m. of metal flakes.

5. A crystal paper as defined in claim 4, wherein said filmforming substance in said second coating layer is rosinmodified phenol resin, said metal powder is aluminum powder, said crystals of inorganic metal salt consist of magnesium sulfate, and said film-forming substance in said first coating layer is dextrin.

6. A crystal paper as defined in claim 4, wherein said metal powder has the form of flakes of a size of about 0.3;tXl0 ;I.X30;L7.

A crystal paper having a metallic luster, comprising a paper substrate, a coating layer on said paper substrate and consisting essentially of (1) crystals of a crystalline organic compound selected from the group consisting of o-aminophenol, 2,4-dinitrophenol, p-nitroaniline, resorcinol, 3- hydroxy-2-naphthoic acid, anthraquinone-l-sulfonic acid, acetanilide, acetoacetic anilide, dimethyl terephthalate and pchloroaniline and (2) metal flakes, dispersed in a substantially water-insoluble film-forming substance, said coating layer containing 4-15 g./m. of the crystalline organic compound, 2-10 g./m. of metal flakes, and 5-l8 g./m. of the film-forming substance.

8. A crystal paper as defined in claim 7, wherein said filmforming substance is nitrocellulose, said crystals of a crystalline organic compound consist of acetanilide, and said metal flakes are aluminum flakes.

9. A crystal paper as defined in claim 7, wherein said crystalline organic compound has a melting point above 50 C. and is not vulnerable to deliquescence or sublimation at the room temperature.

10. A crystal paper as defined in claim 7, wherein said metal powder has the form of flakes of a size of about 0.3;4Xl0 30;i. 

2. A crystal paper as defined in claim 1, wherein said first coating layer consists of magnesium sulfate, gum arabic, aluminum flakes and brass flakes, while said second coating layer consists of nitrocellulose.
 3. A crystal paper as defined in claim 1, wherein said metal powder has the form of flakes of a size of about 0.3 Mu X 10 Mu X 30 Mu .
 4. A crystal paper having a metallic luster, comprising a paper substrate, a first coating layer on said paper substrate and consisting essentially of crystals of an inorganic metal salt selected from the group consisting of magnesium sulfate, barium chloride, ammonium sulfate and stannous chloride and a water-soluble film-forming substance, and a second coating layer on top of said first coating layer and consisting essentially of metal flakes dispersed in a substantially water-insoluble film-forming substance, said second coating layer containing 3-6 g./m.2 of metal flakes.
 5. A crystal paper as defined in clAim 4, wherein said film-forming substance in said second coating layer is rosin-modified phenol resin, said metal powder is aluminum powder, said crystals of inorganic metal salt consist of magnesium sulfate, and said film-forming substance in said first coating layer is dextrin.
 6. A crystal paper as defined in claim 4, wherein said metal powder has the form of flakes of a size of about 0.3 Mu X 10 Mu X 30 Mu .
 7. A crystal paper having a metallic luster, comprising a paper substrate, a coating layer on said paper substrate and consisting essentially of (1) crystals of a crystalline organic compound selected from the group consisting of o-amino-phenol, 2,4-dinitrophenol, p-nitroaniline, resorcinol, 3-hydroxy-2-naphthoic acid, anthraquinone-1-sulfonic acid, acetanilide, acetoacetic anilide, dimethyl terephthalate and p-chloroaniline and (2) metal flakes, dispersed in a substantially water-insoluble film-forming substance, said coating layer containing 4-15 g./m.2 of the crystalline organic compound, 2-10 g./m.2 of metal flakes, and 5-18 g./m.2 of the film-forming substance.
 8. A crystal paper as defined in claim 7, wherein said film-forming substance is nitrocellulose, said crystals of a crystalline organic compound consist of acetanilide, and said metal flakes are aluminum flakes.
 9. A crystal paper as defined in claim 7, wherein said crystalline organic compound has a melting point above 50* C. and is not vulnerable to deliquescence or sublimation at the room temperature.
 10. A crystal paper as defined in claim 7, wherein said metal powder has the form of flakes of a size of about 0.3 Mu X 10 Mu X 30 Mu . 